1. Field of the Invention
Until quite recently, the diesel fuel oil compositions burned in or employed to power diesel locomotives and diesel motor vehicle were the heavier diesel fractions generally boiling from about 300.degree. to about 650.degree. F. These diesel fuel oil compositions were very satisfactory from an engine wear standpoint and also were efficient functionally as well as being economical. The one serious drawback that these fuel oil compositions possess, however, is that they are not clean burning fuels and in use give rise to significant amounts of smoke pollution. Because of new environmental standards, the use of such fuel oil compositions has been seriously limited or completely restricted generally by statutory measures.
A significant shift to lighter and cleaner burning diesel fuel oils was made in order to overcome the noted emissions or pollution problem of the heavier diesel fuels and thus meet the new statutory standards. The lighter diesel fuel oil compositions are very satisfactory from the pollution standpoint i.e., they meet or surpass the regulatory limits on smoke and exhaust emissions. Unfortunately, the lighter diesel fuel oils are notably deficient in lubricity or lubricating properties with the result that engine wear from the use of the light diesel oil fuels in internal combustion reciprocating diesel engines became a very serious problem. Lubricity agents were added to the light diesel fuel oils to overcome the wear problem but with mixed results. In some cases involving the so-called light diesel fuel oils, lacquer formation in the fuel injectors have been found to seriously interfere with the proper operation of the diesel engines.
2. Description of the Prior Art
U.S. Pat. No. 2,632,695 discloses rust inhibited light petroleum products including gasoline, naphthas and burning oils in which the rust inhibitor employed comprises dimeric or tri-meric acids produced by the condensation of two or three monomers of an unsaturated aliphatic monocarboxylic acid or hydroxy aliphatic monocarboxylic acid having between about 16 and 18 carbon atoms per molecule.
U.S. Pat. No. 3,228,758 discloses distillate hydrocarbon fuels, such as gasoline, kerosene, fuel oils, diesel fuels and furnace oils, inhibited with respect to color and haze formation, rust inhibited, and inhibited in the formation of ice in the carburetor passage of automobile engines due to the incorporation therein of a normally liquid completely or partially neutral amine salt of branched chain primary alkyl acid esters or ortho-phosphoric acid in which each esterifying alkyl group contains 13 to 16 carbon atoms and the amine is an aliphatic hydrocarbon monoamine of 6 to 24 carbon atoms in which each aliphatic hydrocarbon radical is attached to the nitrogen through a saturated carbon atom.